Turn stagnant bodies of water (public reservoirs, lakes too polluted to suport life, etc.) into solar collectors, either by using the the water itself to absorb the energy, or by floating a net of connected solar collectors across the surface.
After all, the water's just sitting there.-- funcrusher, Feb 26 2001 OTEC http://www.mrtc.org/~mist/ote.htmlOcean Thermal Energy Conversion [reensure, Feb 26 2001] Thermoelectric Power Generation http://www.epa.gov/...er_with_america.htm47% of the demand for water in the U.S. [reensure, Feb 26 2001] Hydrodynamics of a pump http://www.thepump.org/pumpoperation.htmtechnobadger--this is cool speculation. [reensure, Feb 26 2001] Solar Pond http://en.wikipedia.org/wiki/Solar_pond [afinehowdoyoudo, Dec 11 2009] The OTEC site link to the left is a fine example of heat exchange technology. Some of the evaporation and fluid pressure dynamics support a bizarre theory of why there are a series of empty chambers under Gaza's great pyramids, but that is another story.-- reensure, Feb 26 2001 Forgive my ignorance as to the nature of reserviors. I thought hydroelectric dams were powered by water as it flowed over turbines. But still, for polluted bodies of water that are sitting out in the open a floating net of collectors might be useful.-- funcrusher, Feb 26 2001 what about the fishy's-- edski, Feb 27 2001 reensure- Giza pyramids(?)-- technobadger, Feb 27 2001 sure thing, ravenswood. let me know when you've got (based off of degroof's figures) $1,672,704,000,000 laying around. :)-- absterge, Feb 28 2001 You wouldn't use photovoltaic cells for large-scale solar power production. You'd use an array of concentrators. The land requirement is about 5 acres/megawatt. When you consider the mining requirements for fossil fuel plants, the land usage is about the same.
7% efficiency is pretty bad for modern photovoltaic cells. Most of the producers targeting the home market shoot for around 15%-20%.-- francois, Mar 01 2001 This thread has been quiet for a month or so and I have just discovered the site. Could anyone confirm this discussion thread is still extant?-- archimedes, Apr 12 2001 Hmmm... So if I buy the solar array, it'll pay for itself within my mortgage's lifetime.-- phoenix, Jul 20 2001 One plus point to floating solar panels on the surface of reservoirs is that you would cut down on water wasted through evaporation. The reduced oxygen interchange would probably kill the fishies though. Still, if you actually wanted to produce hydrogen rather than electric current, an integrated modular solar panel/electrolytic cracker would be worth investigating.-- BunsenHoneydew, Oct 22 2002 Better yet, have the sun heat the water, making some of it evaporate. Then, as the water rises, it condenses into large vapourous masses. After that, have differences in air pressure push these masses up against mountain ranges or to higher elevations. This would make the water condense even more, making it heavier leading to its fall to the ground. Collect this water in a big tub, then use its new potential energy to turn a turbine attached to a generator!
So... do I have a Nobel Prize or what?-- rapid transit, May 17 2003 Rough numbers, 11% effeciency is not unheard of. And the planet uses about 10 terrawatts annually.-- belg4mit, May 17 2003 I can't remember the geographical location, but some people proposed making a hydroelectric dam in a certain area some time back (before they had computers that could simulate all the fluid and structural dynamics, etc) and so they built a scaled down model of all the geography to test it. They discovered that the rate of evaporation would make the whole idea impossible. But using this idea to prevent evaporation and harness some extra power to boot just might be a good idea in this situation.
Even if the solar cells weren't efficient enough in and of themselves to be worth the overhead, they would eliminate the obstacle to harnessing a great deal more energy in this particular case. And maybe in others.-- Anarch, Apr 09 2004 Solar power is an underdeveloped technology. with research I'm sure efficiency could be improved. As for floating solar panels on unused bodies of water, why not; as mentioned it's not being used any other way.-- 5th Earth, Apr 09 2004 [funcrusher]i think the idea is really good. although the discussion has been diverted to solar cells etc, if i have understood correctly, i support & augment your ideas as:a) floating collectors would help avoid occupation of land for equal energy collection, b)as you have mentioned about water bodies heavily polluted to support life,there would be no possibility for fishing etc. so these can be converted to solar ponds-a very old & proven concept.details of solar pond can be obtained easily on the net.-- vedarshi, Apr 09 2004 And further, add an air pumping system to the bottom of the lake. This will oxygenate the water to compensate for the loss of exposed surface.
However the lack of light will kill any plant life in the water, so you'll probably still have a dead lake.
OTOH no-one ever said this thing has to cover the whole lake. If it was only a portion, vegetation would still grow elsewhere, and the panels would provide a shady spot for stressed fishies to hide out on a hot day.
And integrated water cooling will keep the efficiency of those panels up nearer their rated max.-- BunsenHoneydew, Jun 28 2006 //You wouldn't use photovoltaic cells for large-scale solar power production. You'd use an array of concentrators. The land requirement is about 5 acres/megawatt. When you consider the mining requirements for fossil fuel plants, the land usage is about the same.//
Say what now? Did the voices tell you that?
...This is a big idea about making incredibly low "quality" power. Thermodynamics tells us that changing a body of water's temperature by a few single degrees might well take a great deal of energy - but you're only ever going to be able to use a tiny little fraction of that energy in any useful way. "entropy is a harsh mistress" as they say.-- Custardguts, Dec 09 2009 Yes, thermodynamics rules with an iron fist, without even a velvet glove to soften the grip. But the challenge of solar power is not about efficiency... all that energy ends up as heat anyway. The real challenge is cost, and it may be that a huge, cheap, inefficient collector is the best deal, at least in the short term. Say a salt pond developed a delta-T of 40C, that puts the max efficiency at about 10% or better..-- afinehowdoyoudo, Dec 12 2009 random, halfbakery